Surface-treated materials and method for making them

ABSTRACT

The invention relates to a surface treated mineral material and a process for producing the same by means of laser treatment and water proofing. A preferred planned use of the invention relates to the surface and wall coverings, made of natural and artificial stones for indoor and outdoor areas, optimized, in particular with respect to wear resistance, stain resistance and slip resistance.

The object of the invention relates to a surface-treated mineralmaterial and a process for their production. A particular planned use ofthe invention relates to surface optimized floor and wall coverings madefrom natural or artificial stone for indoor and outdoor areas, inparticular optimized with respect to wear resistance, soil repelling andslip resistance.

Slips are one of the most frequent causes of accidents in Germany. Theseverity of such accidents is usually underestimated. In order toincrease the security of footsteps the shoe soles and floors both mustbe embodied in a slip resistant manner. Predominantly, this is necessaryin floor coverings that are exposed to slip enhancing media. In manyareas of public life, e.g., on side walks and public courts, and, inprivate areas as well it is common to use blasted, singed, kerneled,layered, smooth, or serrated, polished, and etched floor coverings indry as well as in wet areas and transitional areas. In addition to theiruse as floor coverings, such coverings are also used for wall andfrontal surfaces, preferably in outdoor regions, but in indoor regionsas well. Here, it is desirable to durably maintain the slip resistanteffect and, simultaneously, achieve a surface as stain resistant,washable, and wear resistant as possible, that is embodied with steampermeable, hydrophobic, and oleophobic features.

Frequently, indoor and outdoor floor and wall areas are covered withnatural and artificial stone. A variety of regulations must be observedin relation to security of footsteps. Thus, in many areas only heavilystructured surfaces can be used. Such surfaces have production-relateddisadvantages.

The evaluation of surfaces can be performed, e.g., according to thefollowing standardized processes:

DIN 51130, the determination of the slip resistant characteristics forwork places and work areas exposed to danger of slipping,

DIN 51097, the determination of the slip resistant characteristics forwet loaded bare foot areas —stepping processes,

ASTM 1028, static coefficient of friction or

ISO 10.545 part 17 (Method B: Static Slider).

A variety of processes exist for the production and/or increase of slipresistant characteristics of floor coverings and for the production ofvarious surface appearances and surface characteristics as well.Predominantly, their utilization depends on where and how the surface isto be used and what the builder requests with regard to surfaceappearance and surface characteristics. In the following, the mostessential processes are briefly described:

1. Blasting

In blasting a blasting material corresponding to a desired roughness isthrown with high pressure onto the surface. The more or less hardblasting material causes an uneven roughness provided-with microroughness and deadening of the surface. Additionally, production relatedfine dust particles adhere more or less durably to the stone surface inor at the joint mixtures.

2. Flame Jet Singeing

In flame jet singeing highly energetic fuel gas —oxygen flames arecreated by which the surfaces to be treated are briefly heated to alarge extent. Due to the effect of the flames, the quartz crystals inthe uppermost regions of the stone burst and parts of the stone melt;subsequently it solidifies in a glasslike manner, adheres comparativelyloosely to the surface, and peels off when used.

3. Kerneling

Kerneling occurs by using a kerneling tool (kerneling hammer) which isprovided with several, evenly positioned chisel tips. During thecontinuous motion of a work piece the kerneling hammer impacts thesurface with a certain frequency. This results in a more or less intenseshock of the composition with chippings and loosely or tighter adheringstone parts, dependent on the stone components. Production relatedsuperfine dust particles adhere more or less tightly in or to thecomposition mixtures.

4. Surface Coating

The coating of surfaces can be performed such that the surfaces areprovided with, e.g., knobs and, thus, an increase in slip resistance isachieved. The stone is closed over its entire surface. This isdisadvantageous after laying, since the water used for laying is blockedand the stone is damaged by rising water (steam pressure develops, e.g.,which can burst the stone). The modification of the appearancecharacteristics is correlated to the coating used; this method is onlyof limited use in floor coverings, since wear cannot be prevented.

5. Rough Charging

In ore processing (blocks of natural or artificial stone), iron sawblades cut the blocks into rough slabs with a steel-sand mixture beingadded. Thus resulting in an unevenly rough surface. Production relatedfine dust and residue of the steel-sand mixture adhere in or at thestone surface. Depending on the type of stone and the present residue,corrosion processes begin when coming into contact with water, which canpartially result in bursting of the composition and discolorationdepending on the duration of the exposure.

6. Serrating

In ore processing (blocks of natural or artificial stone), iron sawblades cut the blocks are cut by means of diamond-stocked metal sawblades directly into standard size. Thus, resulting in a surfacecomparable to coarse polishing. The quickly rotating cutting disc andthe continuous introduction of water press the production related finedust particles into the natural formation of the stone surface. Thesefine dust particles partially adhere tightly to the stone formation;however, they separate from floor coverings when said floor is used.

7. Chemical Etching

Generally, in chemical etching of stone surfaces (using substancescontaining hydrofluoric acid) the soft parts are washed out first. Thechemical composition and concentration must be adjusted to the stonesurface, in order to prevent undesired damage, such as corrosion, forinstance. Health hazardous vapors develop during processing.

8. Cutting and/or Polishing

Treatment of the surfaces by means of an abrasive medium, such asdiamond dust, boron nitride, or corundum (fused alumina).

The described processes or similar processes using abrasive media and/orchisel-like tools achieve an increase in security of footsteps, however,they also cause structural shocks and chippings off the formation and,production related superfine dust particles deposit, partially adheringtightly. In some processes, it is also disadvantageous that the slipresistance is only achieved subsequent a post treatment at the point ofuse.

From DE A 2 053 110 a process for treating mineral surfaces is knownwith the surface initially being hydromechanically and subsequentlytreated with organo-silicide compositions causing hydrophobic effects.However, surfaces treated in such a way are not provided with thedesired stain resistance.

From DE 195 18 270 a surface treated, slip resistant floor covering isknown that does not show some of the above-mentioned disadvantages. Sucha floor covering is produced by applying statistically distributed microcraters, invisible for the human eye, onto the surface of the floorcovering by means of a laser.

The object of the invention is to provide highly slip resistant, stainresistant, and durable, wear resistant, weather resistant, free of finedust, and optionally, refined surfaces, e.g., by means of polishing,made from mineral materials which are not provided with any of thedisadvantages of prior art.

The object is attained according to the invention by providing aprocess, having at least two steps, for treating the surface of mineralmaterials, which comprises the following steps:

a) Laser radiation affecting the surface and

b) Application of an organo-silicide composition onto the surface.

The object of the surface treatment are mineral materials such as:natural stones, artificial stones, e.g., mineral agglomerates of resincompositions or cement compositions, ceramics or ceramic materials,earthen ware, or stone ware. The above-mentioned steps are preferablyparts of a treatment process, essentially limited in duration, and occurprior to further treatment/utilization as a mineralmaterial/construction material.

The object of the process according to the invention can be untreated orpretreated mineral materials. Part of the pretreatment of the surfacecan be a surface treatment by means of blasting, singing, kerneling,coating, rough charging, sawing, cutting, and/or etching, as mentionedabove. Furthermore, prior to one of the above-mentioned steps (a) and(b) according to the invention, the surfaces are advantageously clearedof loosely adhering particles by means of a mechanical surface cleaning,such as brushing, washing or blowing.

Work pieces treated this way, if necessary, are exposed to the lasertreatment of step (a) in the following described in detail.

Step (a): Laser Treatment

According to the invention, a removal of loose particles from thesurface and a “welding” or glazing of existing micro fractures performedby the effect of laser radiation, in particular, laser impulses. Thus, asurface is achieved that can accept the preferably subsequentwaterproofing.

Essential parameters of the laser treatment are:

diameter of the treatment area, i.e., lateral extension of the laserinduced surface indentation,

pulse duration (duration of impact) and pulse energy, i.e., depth of thelaser induced surface indentation and, corresponding to the wave lengthof the laser, the type of interaction, i.e., evaporation/melting and the

distance of the impact areas, e.g., number and distribution of laserinduced surface indentations.

Shape, depth, and width of the laser induced surface indentations arepreferably adjusted such that a shallow indentation develops in theshape of a lens. The indentation in the shape of a lens according to theinvention is an indentation whose maximum depth does not exceed half ofthe average lateral extension of the deepest point of the indentation.

These parameters can be controlled and adjusted to each material and thepreferably subsequently performed step of the surface treatment using anorgano-silicide composition for controlling the absorbability of thesurface of the mineral material. The above-mentioned parameters shouldbe adjusted preferably such that the removal of material is essentiallydistributed evenly over the surface to be treated and occur essentiallyby means of evaporation. Consider the material characteristics, itshould be practically achieved to introduce a high amount of energy in avery short period of time. In case of treatment of mineral surface madefrom natural stone (e.g., granite) the pulse energy has a value ofpreferably 0.4 mJ to 1.5 mJ, a pulse duration of preferably 30 ns to 400ns.

The laser radiation can be created with the aid of x-ray lasers,solid-matter lasers such as Nd-YAG-lasers or HD-lasers, fluid lasers, orgas lasers, such as CO₂-lasers. Preferably, pulsed lasers are used.

Preferably, lens-shaped surface indentations are created by a purposefuleffect of impulse laser beams according to the invention. Productionrelated existing structural fractures are smoothened or welded withinmilliseconds by the effect of punctual heating of micro areas coveringthe entire surface and loosely or tightly adhering superfine dustparticles are evaporated. Depending on the material of the floorcovering, the laser parameters, such as energy density, pulse duration,etc., are preferably selected such that the removal of material forcreating the surface indentations, the surface smoothening, the weldingof stone compositions, and the evaporation of superfine dust particlesoccur essentially by evaporation.

The deflection of the laser beam over the surface occurs by mean s ofdesign components known per se, such as, e.g., the ones known from theiruse for labeling or for surface inspections (scanners and polygonalreflectors in connection with plane field optics).

Contrary to the processes of singeing, kerneling, rough charging, andblasting super fine laser structuring concerns a touchless process(further processing) of the surface. The process according to theinvention eliminates the results of mechanical construction shocks. Theadhesion of super fine dust particles and production related more orless loose stone compositions are evaporated by the laser treatment orchipped off so that an absorbable surface is created for the, preferablysubsequent, surface treatment with organo-silicide compositions.Furthermore, the processing step of the laser treatment is characterizedin a good controllability of the parameters, i.e., density, depth, anddiameter of the micro pores, welding, and smoothening of the surface canbe adjusted by the computer controlled use of laser parameters accordingto the respective requirements of the various surfaces and stones.

The slip resistant feature of the, e.g., previously blasted, singed,kerneled, layered, rough charged or serrated, polished and/or etchedsurface is not negatively influenced by the laser treatment, butgenerally enhanced. The national and international standards for slipresistant surfaces are achieved and/or exceeded. Certainly, adestruction of the macroscopic surface of stones can be excluded. Thisis achieved by statistically unevenly distributed indentations (microcraters), having a suction effect, being provided on the surface,preferably covering the entire surface and being as flat as possible andbeing preferably invisible for the human eye. In this case, invisiblemeans that the human eye when seen from a certain distance, due to itsresolution behavior does not perceive the surface indentations as such.In optimal lighting conditions, the resolution limit is assumed atapproximately one angular minute for viewers of normal sight. Therefore,from a minimal viewing distance of 1.5 m (standing adult man) a craterof a maximal lateral expanse of 0.44 mm is barely visible.

Preferably, the laser induced surface indentations (micro craters) areprovided with a diameter of 5-900 Am, in particular preferably 10 to 150μm, and with a depth of 10 to 400 μm, in particular preferably of 20 to200 μm. Advantageously, the surface (hypothetically entirely planesurface) contains at least 2.5 million laser induced surfaceindentations per m², preferably 3.5-20 million. Laser induced surfaceindentations per m². Furthermore, the distance of the surfaceindentations should not be larger than 10 to 250 μm (determined by thesmallest distance of the circumference of two surface indentations). Thelaser induced surface indentations may overlap as well.

When using non-pulsed lasers, such as C0 ₂-lasers for instance, thesurface can be treated with a laser beam of variable diameter withoutdirectly creating pores, as well. Such a treatment can be considered acontinuous melting process on the surface. Sometimes, a surfacetreatment of such type does not provide the above-mentioned laserinduced surface indentations.

Step (b): Plane Application of an Organo-silicide Composition (CalledWater Proofing or Water Proofer in the Following)

Water proofers are organo-silicide compositions or compounds containingsuch. An organo-silicide composition according to the invention is acomposition that is provided with at least one silicon-oxygen-carboncompositions sequence per molecule and/or at least one silicon-carboncomposition per molecule. Appropriate organo-silicide compositions arealso such containing several silicon atoms of which at least two have anoxygen atom, an oxygen-hydrocarbon-composition, anoxygen-hydrocarbon-oxygen-composition, or a hydrocarbon-composition.Additionally, the organo-silicide composition can carry functionalgroups as well, such as halogen, in particular hydroxy, chlorine, amino,carboxy, cyano, methacryloxy, epoxy, mercapto, or vinyl groups. Suitableorgano-silicide compositions are, among others, alkylsilanole,alkylalkoxysilane, alkoxysilane, oligo- and polysiloxane, and silicone.Additionally, the organosilicide compositions can contain metal atoms aswell, such as zirconium, aluminum, or titanium, e.g., in the form ofSi—O—M, SiO-Alkylen-O—M, Si-Aldylen-O—compositions (M=A1, Zr, or Ti).Preferably, the organo-silicide composition contains predominantly, inparticular, preferably at least 80 atom %, in particular at least 90atom %, silicone, oxygen, carbon, and hydrogen atoms.

It is particularly advantageous for the water proofers to contain anaqueous dispersion of the organo-silicide composition in water. Adispersing agent can be the object of such compositions as well.However, the organo-silicide composition can be a hydrocarbon medium aswell, such as mineral turpentine.

A dispersion of an alkylalkoxysilane and a fluoropolymer in water hasproven to be a particularly advantageous water proofer, such as the onedistributed by the name of Wacker BS29 (0142200) from the company WackerChemie GmbH. Another product called Wacker BS 28 can be used as well,however, it is less well suited.

The advantage of the pretreatment by laser effect consists, amongothers, in the even absorption of the water proofing caused thereby,since in the initial treatment step, any soiling and deposits arecleared from the surface and the water proofer can penetrate into thenatural hollow spaces of the stone structure.

The surface provided with such a water proofing is not or only to asmall extent limited in its diffusion of water vapors. Thus, theconstruction material can continue to “breathe” (diffuse) on its bottom,like in the non-water proofed state. Due to the hydrophobous andoloephobous effect of the water proofing agent the surface is protectedfrom absorbing water and impurities such as grease, oil, paint, coffee,coke, tea, urine, red wine, and acid rain, and/or such soiling can beremoved more easily since it can not penetrate into the stone structure.

Additionally, the water proofing subsequent to the laser treatment hasthe advantage in reference to waterproofing of stone surfaces notpretreated according to step (a), blasted, singed, kerneled, layered,charged, serrated, polished or etched that it can be designed waterbased. Conventional water proofers, used after laying, are based onmineral turpentine and their use carries threaten health andenvironment. Without prior laser treatment the water proofer cannotpenetrate evenly into the stone structure and adheres to the productionrelated superfine dust and soil residue. When using such surfaces, notpreviously having been treated by laser effect, loosely adhering fineparticles can be separated together with the water proofer. Thus, thewater proofing effect is torn and compromised.

The application of the water proofer occurs preferably by means of adosing device and a plane application of the water proofer/a waterproofing composition. According to a preferred embodiment the preferablyliquid water proofer/water proofing composition is applied by means ofrolls evenly depositing the liquid onto the surface of the mineralmaterial. The water proofer is applied such that an even penetrationdepth is guaranteed and the deposition of excess amounts on the surfaceare prevented.

The process can be improved such that subsequently to the lasertreatment and the water proofing another process is performed by meansof thermal heat, microwave treatment, UV —or IR-radiation, or lasertreatment, either resulting in recrystallization of the surface due tomild temperatures or a fusion of the organo-silicide composition withthe carrier material at high temperatures. According to a preferredembodiment of the invention, the temperature limit on the surface of themineral material of, e.g., 75 ° C. should preferably not be exceeded.

According to another embodiment of the invention, the stone surface isexposed to a hydro mechanical post processing according to DE 197 15 937subsequent to the laser treatment and prior to the waterproofing. Here,a preferably acrid cleaning solution is applied onto the surface of themineral material, preferably by means of the effect of a device formechanical surface cleaning, such as a brush. Furthermore, preferablyafter said cleaning solution has affected the surface the cleaningsolution is removed/rinsed off and/or neutralized by means of anothercleaning solution to be applied.

Furthermore, it is advantageous to heat the surface prior to applyingthe water proofer. This processing step prepares the surface for theapplication of the water proofer. The heating of the surface can beperformed such that selectively determined regions of the surface, i.e.,punctual or area sections and/or particularly certain layers of thesurface are heated (e.g., above 25° C. or above 35 ° C.)

According to another embodiment of the invention, before, after, orpreferably simultaneously with the water proofing step or in the waterproofing composition respectively a color changing, color intensifyingaddition can be applied onto the surface, such as a brightener, a colorpigment, or a soluble dye. This addition can sometimes be chemicallyattached to the water proofer.

The surfaces produced according to the invention are characterized,e.g., in a reduced absorption capacity for water. Preferably, at least50 % less water is absorbed by surfaces processed according to theinvention in reference to an untreated surface (i.e., a surface prior tobeing exposed to the process according to the invention).

The process according to the invention comprises a flexible,environmentally friendly process for producing surfaces covering,meeting requests and suiting demands, comprising advantages in relationto conventional surfaces with regard to wear resistance, stainresistance, water absorption, absence of micro fractures, and slipresistance. An important advantage of the process according to theinvention is its problem-free integration into the production process ofthe coverings. Compared to an unprocessed mineral surface the followingcharacteristics are improved: wear resistance, stain resistance, surfacecompacting, and micro fractures are smoothened/bonded.

Therefore, the mineral material provides laser induced surfaceindentations and a laser induced smoothening of the surface with a laserinduced surface removal occurring in the shape of “lines” in case anon-pulsed laser is used, however, no point-shaped surface indentationsare created. The organo-silicide composition can be verified on thesurface of the mineral material, particularly in the pore areas near thesurface of the mineral material, sometimes even up to a depth of 0.5 to1 cm, depending on the stone. In a post treatment of the water prooferusing higher energy a reaction product of the organo-silicidecomposition can be proven with the surface of the mineral material and/or a thermal decomposition product.

Since the water proofer penetrates the stone structure and does notadheres to loose particles, which wear off and separate duringutilization the surface of the mineral material provides a visually evenappearance even after continuous use. This means that in the case offloor coverings the architect or builder can examine the characteristicsof, e.g., a floor covering of natural stone prior to laying, and asubsequent processing and, thus the visual change of the floor connectedtherewith is unnecessary or, in most cases, even impossible.

In the following, a processing progress is described with reference toFIG. 1.

1 A brush for removal of dry impurities. Brushing direction preferablyopposite the belt direction.

2 A laser unit

3 A dosing, station for cleaning solution containing tensides, acidsand/or bases

4 A brush cleaning station subsequent to the application of the cleaningsolution. Brushing direction preferably opposite to the belt direction,if necessary, subsequent to the brush cleaning station 4, additionaldosing stations for cleaning solution and brush cleaning stations mayfollow (not shown)

5 A brush cleaning station for residue-free removal of adhering and/orin the previous stations diluted components. Brushing directionadjustable to the belt travel direction or opposite thereto; speed,type, and shape of the brushes are variable.

6 A suction device for suctioning the diluted components and liquidresidue.

7 A drying station, drying by means of micro waves, infrared, hot air,laser treatment, or thermal heat

8 A dosing unit for the water proofer: plane application of the waterproofer

9 A drying station, drying by means of micro waves and/or infrared, hotair, laser treatment, or thermal heat, e.g., by means of introducing air

10 A work piece on the conveyor

11 A Conveyor Device

EXEMPLARY EMBODIMENT

Object:

floor covering made of natural stone, slip resistant when affected byslip-enhancing agents according to existing regulations, stainsprotected, proofed against the absorption of water and oil by ahydrophobic and oleophobic surface, laid in indoor and outdoor areas oftrain stations.

Realization:

Surface treatment by means of a Nd-YAG-laser, energy denity of 19 J/cm²,pulse duration of 100 ns, focal distance of 300 mm, focusing onto thematerial surface, relative movement between the laser focus and the workpiece occurs preferably by means of a optical deflection in they-direction and by work piece transportation in the x-direction. 1impulse per created microcrater each, diameters of created craters inthe range from 0.2 to 0.8 mm, distance of the craters in the x- and they-direction 0.1 mm, created depth 0.05 mm.

Subsequent mechanical cleaning by means of brushing and vacuuming oflarger dust particles, washing of the surface by means of rotatingbrushes with the use of acids and bases, drying, water proofing usingthe plane application of an aqueous dispersion containingalkylalkoxysilane and fluorpolymer (Wacker BS 29), and final thermaldrying.

What is claimed is:
 1. A process for surface treatment of mineralmaterials including a least the following steps a) Applying laserradiation onto the surface and b) Applying an organo-silicidecomposition onto the surface, with the above-mentioned steps (a) and (b)being part of a treatment process essentially limited in time and whichoccur prior to further processing and/or use of said mineral materials.2. A process according to claim 1, characterized in that by means of theeffect of laser radiation laser induced surface indentations are createdwith an average diameter of 5 to 900 μm.
 3. A process according to claim1 characterized in that by the effect of laser radiation laser inducedindentations are created with an average depth between 10 to 400 μm. 4.A process according to claim 1, characterized in that by the effect oflaser radiation at least 2.5 million surface indentations per m² arecreated.
 5. A process according to claim 1 characterized in that as anorgano-silicide composition alkylsilanole, alkylalkoxysilane,alkoxysilane, oligo and polysiloxane and/or silicone is applied,sometimes having one or several of the following functional groups:hydroxy, halogen, in particular, chlorine, amino, carboxy, cyano,methacryloxy, epoxy, mercapto, or vinyl.
 6. A process according to claim1, characterized that the organo-silicide composition is applied in theform of an aqueous dispersion.
 7. A process according to claim 6characterized in that the organo-silicide composition is applied in theform of an aqueous dispersion containing a dispersing agent.
 8. Aprocess according to claim 6 characterized in that the organo-silicidecomposition is applied in the form of an aqueous dispersion togetherwith a fluorpolymer fluoropolymer.
 9. A process according to claim 1,characterized in that subsequently to the application of theorgano-silicide composition a surface treatment is performed by means ofthermal energy, UV- or IR- radiation, microwaves and/or lasers.
 10. Amineral material produced according to the process of claim 1,characterized in that it is provided with A) laser induced surfaceindentations, a laser induced surface removal and/or a laser inducedsmoothening of the surface and B) an organo-silicide composition ontothe surface and/or in the pore space of the mineral material near to thesurface.
 11. A mineral material according to claim 10, characterized inthat the laser induced surface indentations are provided with an averagedepth of 10 to 400 μm.
 12. A mineral material according to claim 10characterized in that the laser induced surface indentations areprovided with an average diameter between 5 and 900 μm.
 13. A mineralmaterial according to claim 10 characterized in that the surface isprovided with at least 2.5 million laser induced surface indentationsper m².
 14. A process according to claim 2, characterized in that bymeans of the effect of laser radiation laser induced surfaceindentations are created with an average diameter between 10 to 150 μm.15. A process according to claim 3, characterized in that by the effectof laser radiation laser induced indentations are created with anaverage depth between 20 to 200 μm.
 16. A mineral material according toclaim 11, characterized in that the laser induced surface indentationsare provided with an average depth between 20 to 200 μm.
 17. A mineralmaterial according to claim 12, characterized in that the laser inducedsurface indentations are provided with an average diameter between 10 to150 μm.